Segmented large pre-vacuum nitriding furnace

Abstract

The present application relates to the technical field of chemistry, and particularly relates to a sectional large pre-vacuum nitriding furnace, which comprises an outer shell and a nitriding furnace pot, the outer shell comprises a bottom shell and an upper cover, the bottom shell and the upper cover are connected to form a furnace cavity, the nitriding furnace pot is arranged in the furnace cavity, the nitriding furnace pot comprises at least two nitriding pot body units, the plurality of nitriding pot body units are detachably spliced along the front-rear direction of the nitriding furnace pot, a base is arranged in the workpiece loading area of the nitriding furnace pot, and the sectional large pre-vacuum nitriding furnace further comprises an electronic wind system, the electronic wind system comprises a high-voltage power supply and at least two electronic wind generating units; the electronic wind generating unit is arranged in the nitriding furnace pot; the high-voltage power supply is arranged outside the nitriding furnace pot; the electronic wind generating unit comprises a first positive electrode and a first negative electrode; according to the complex workpiece geometric shape, the jet direction of the airflow and the plasma action area are optimized, and directional regulation of the local nitriding intensity is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical technology, in particular to a large pre-evacuation vacuum nitriding furnace. BACKGROUND

[0002] The large pre-evacuation vacuum nitriding furnace is a heat treatment equipment, mainly used for surface nitriding strengthening of metal workpieces, and its core feature is that oxygen and impurities in the furnace are completely removed through a vacuum system before nitriding, and then ammonia gas or nitrogen-hydrogen mixed gas is introduced, so that active nitrogen atoms are allowed to penetrate into the surface of the workpiece to form a high-hardness and high-wear-resistance nitriding layer through plasma-assisted or gas nitriding process in a temperature range of 500-580 DEG C.

[0003] During the operation of the nitriding furnace, the introduced ammonia gas or nitrogen-hydrogen mixed gas is dispersed inside the furnace body. For large-size complex workpieces, the ammonia gas or nitrogen-hydrogen mixed gas cannot uniformly cover the recesses, inner holes and other hidden areas of the workpieces, and thin-walled parts are prone to over-nitriding or deformation, resulting in uneven thickness of the nitriding layer. SUMMARY

[0004] This section is intended to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, the abstract and the title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0005] In view of the problems existing in the prior art, the present application is proposed. To solve the above technical problems, the present application provides the following technical solutions.

[0006] The segmented large pre-evacuation vacuum nitriding furnace comprises an outer shell and a nitriding furnace pot, the outer shell comprises a bottom shell and an upper cover, the bottom shell and the upper cover are connected to form a furnace cavity, the nitriding furnace pot is arranged in the furnace cavity, the nitriding furnace pot comprises at least two nitriding pot body units, a plurality of nitriding pot body units are detachably spliced along the front-rear direction of the nitriding furnace pot, a base is arranged in the workpiece loading area of the nitriding furnace pot, and an electronic wind system is further arranged, the electronic wind system comprises a high-voltage power supply and at least two electronic wind generating units.

[0007] The electronic wind generating unit is arranged in the nitriding furnace pot.

[0008] The high-voltage power supply is arranged outside the nitriding furnace pot.

[0009] The electronic wind generating unit comprises a first positive electrode and a first negative electrode.

[0010] The air outlet of the electronic wind generating unit is directed to the workpiece loading area.

[0011] It also includes a main guide cylinder, wherein the first positive electrode and the first negative electrode are arranged in the main guide cylinder along the front-to-back direction;

[0012] The end of the main guide cylinder is provided with a direction adjustment component;

[0013] The steering assembly includes a bowl-shaped ball holder provided at the end of the main steering cylinder;

[0014] A spherical joint is rotatably connected in the bowl-shaped ball holder;

[0015] The extended end of the spherical joint is connected to a secondary guide cylinder;

[0016] The inner cavities of the main guide tube, bowl-shaped ball holder, ball joint and auxiliary guide tube are connected to form an electronic wind flow channel with adjustable direction;

[0017] It also includes an electron wind acceleration unit;

[0018] The electron wind acceleration unit includes a second positive electrode and a second negative electrode;

[0019] The second positive electrode is fixed to the inner wall of the auxiliary guide cylinder;

[0020] The second negative electrode is connected to a base in the workpiece loading area;

[0021] The first positive electrode and the second positive electrode are connected to the positive electrode of the high-voltage power supply outside the nitriding furnace tank through a high-temperature resistant metal busbar;

[0022] The first negative electrode and the second negative electrode are connected to the negative electrode of the high-voltage power supply outside the nitriding furnace tank through a high-temperature resistant metal busbar.

[0023] In traditional processes, it is difficult for air flow to penetrate deep holes, grooves and other parts of complex workpieces, resulting in uneven nitriding of complex workpieces. Existing technologies usually compensate for insufficient nitriding of deep holes by increasing the concentration of process gas, but this will lead to over-nitriding of thin walls and protruding parts, causing deformation, and the excess process gas is directly discharged without participating in the reaction.

[0024] In the above design, a main guide tube is arranged outside the electron wind generating unit to play a wind guiding role. A bowl-shaped ball holder, a spherical joint and a secondary guide tube are arranged at the end of the main guide tube. The main guide tube, bowl-shaped ball holder, spherical joint and secondary guide tube cooperate to form an electron wind airflow channel with adjustable direction. The direction of the secondary guide tube is adjusted according to the geometric shape of the complex workpiece. The secondary guide tube is directed toward the deep holes, grooves and other parts of the complex workpiece where the airflow is difficult to penetrate, thereby enhancing the airflow impact strength of the part. The secondary guide tube avoids the protrusions and thin-walled parts of the complex workpiece, thereby reducing the airflow impact strength of the part.

[0025] An electron wind acceleration unit is set at the end of the electron wind generating unit to accelerate the directional airflow directed to deep holes, grooves and other parts of complex workpieces where air flow is difficult to penetrate, thereby further improving the nitriding intensity of such parts.

[0026] Through the cooperation of the electron wind generating unit, the direction adjustment component and the electron wind accelerating unit, the differentiated distribution of spatial gas in a closed environment is achieved. Without increasing the concentration of process gas, the utilization rate of process gas is improved, the nitriding efficiency of the surface of complex workpieces is improved, and uniform nitriding of the surface of complex workpieces is achieved.

[0027] The present invention solves the dilemma that in the traditional technology, increasing the concentration of process gas leads to over-nitriding of the bulges and thin-walled parts of the complex workpiece, while reducing the concentration of process gas leads to substandard deep-hole nitriding of the complex workpiece.

[0028] Preferably, the large-scale segmented pre-vacuum nitriding furnace adopts the following process when in use:

[0029] Step 1: Place the workpiece to be processed on a base in the workpiece loading area of ​​the nitriding furnace, and electrically connect the base to the second negative electrode;

[0030] Step 2: Adjust the rotation angle of the auxiliary guide cylinder according to the size and distribution of the workpiece, so that the auxiliary guide cylinder faces the deep holes and grooves of the complex workpiece and avoids the protrusions and thin-walled parts of the complex workpiece;

[0031] Step 3: introducing process gas into the nitriding furnace tank;

[0032] Step 4: Turn on the high-voltage power supply and apply DC voltage to the electron wind generating unit and the electron wind accelerating unit, and cooperate with the process gas to form a directional airflow toward the deep holes and grooves of the complex workpiece, so that a uniform nitride layer is formed on the surface of the complex workpiece.

[0033] Optimization: the auxiliary guide cylinder is a segmented telescopic structure;

[0034] The distance between the end of the secondary guide tube and the workpiece surface on the base is between 100-200mm. The length of the secondary guide tube is adjustable. For complex workpiece surfaces with deep holes or grooves greater than 150mm, the distance between the end of the secondary guide tube and the workpiece surface is shortened to 100mm to strengthen the electron airflow in these areas. For complex workpiece surfaces with deep holes or grooves less than 50mm, the distance between the end of the secondary guide tube and the workpiece surface is increased to 200mm to reduce the electron airflow in these areas.

[0035] Optimization, multiple electron wind generating units are distributed along the front and rear directions and circumferential directions of the nitriding furnace tank.

[0036] Preferably, the first positive electrode and the second positive electrode both use a plurality of needle-shaped electrodes; the plurality of needle-shaped electrodes are arranged circumferentially around a central axis; and the first negative electrode uses a mesh electrode.

[0037] Preferably, the needle-shaped electrode and the mesh electrode are both made of high-temperature resistant metal materials; the high-temperature resistant metal materials used for the needle-shaped electrode include at least one of molybdenum, tungsten or their alloys; the high-temperature resistant metal materials used for the mesh electrode include at least one of molybdenum or molybdenum alloys.

[0038] Preferably, a plurality of grooves are provided on the surface of the needle-shaped electrode; the depth of the grooves is between 10-20 μm, and the spacing between the grooves is between 50-100 μm.

[0039] Preferably, the nitriding furnace is provided with multiple air outlet pipes; the air inlet ends of the air outlet pipes are connected to process gas delivery pipes located outside the nitriding furnace body; the air outlet pipes are directed toward the workpiece loading area of ​​the nitriding furnace body; and the air outlet pipes are spaced apart from the electron wind generating unit. This reduces the possibility of newly injected process gas at room temperature directly impacting the workpiece surface under the action of the electron wind generating unit and the electron wind accelerating unit, thereby reducing the possibility of microcracks forming on the workpiece surface due to the impact of unevenly heated and cooled process gas.

[0040] Preferably, the outlet end of the air outlet pipe is detachably connected to a serpentine tube through a high-temperature resistant flange; the serpentine tube is fixed to the inner wall of the nitriding furnace tank; the air outlet of the serpentine tube is not less than 200 mm and not more than 500 mm away from the first positive electrode, and the air outlet direction of the serpentine tube is toward the processing workpiece loading area.

[0041] In summary, the present invention has the following beneficial effects:

[0042] 1. An ionization electric field is formed between the first positive electrode and the first negative electrode, so that part of the process gas flowing through the electric field is ionized. The charged particles generated by the ionization migrate in a direction toward the first negative electrode under the action of the electric field. Momentum transfer occurs when the charged particles collide with neutral gas molecules, and cooperate with the main guide cylinder to form a directional airflow toward the loading area of ​​the workpiece. By setting a direction adjustment component, the direction of the secondary guide cylinder can be adjusted relative to the main guide cylinder, and the secondary guide cylinder is adjusted to point to the deep holes, grooves and other parts of the complex workpiece where the air flow is difficult to penetrate, so that the process gas can be accurately delivered to the deep holes, grooves and other parts of the complex workpiece where the air flow is difficult to penetrate, thereby enhancing the airflow impact strength at this position, avoiding the protrusions and thin-walled parts of the complex workpiece, reducing the airflow impact strength at this position, and achieving uniform nitriding on the surface of the complex workpiece without increasing the process gas concentration.

[0043] 2. By setting up an electron wind acceleration unit and cooperating with the electron wind generation unit, a stepped electric field is established to achieve the doubling of the airflow kinetic energy, further enhancing the impact strength on deep holes, grooves and other locations of complex workpieces where airflow is difficult to penetrate, thereby improving the nitriding uniformity of complex workpieces and improving the utilization rate of process gas.

[0044] 3. The outlet end of the air outlet pipe is far away from the electron wind generating unit, reducing the possibility of the newly injected process gas at room temperature directly impacting the workpiece surface under the action of the electron wind generating unit and the electron wind accelerating unit, so that the newly injected process gas is preheated by the nitriding furnace tank and then reaches the workpiece surface in cooperation with the electron wind generating unit and the electron wind accelerating unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive work. Among them:

[0046] Figure 1 It is a schematic diagram of the overall structure of the segmented large-scale pre-vacuum nitriding furnace of the present invention;

[0047] Figure 2 This is a schematic side view of the overall structure of the segmented large-scale pre-vacuum nitriding furnace of the present invention;

[0048] Figure 3 This is a schematic diagram of the internal structure of the nitriding furnace tank of the segmented large-scale pre-vacuum nitriding furnace of the present invention;

[0049] Figure 4 It is a schematic diagram of the serpentine tube structure of the segmented large-scale pre-vacuum nitriding furnace of the present invention;

[0050] Figure 5 This is a schematic cross-sectional view of the bowl-shaped ball holder of the segmented large-scale pre-vacuum nitriding furnace of the present invention.

[0051] In the figure, 1. outer shell; 101. bottom shell; 102. upper cover; 2. nitriding furnace tank; 3. electron wind generating unit; 301. first positive electrode; 302. first negative electrode; 303. main guide tube; 304. insulating bracket; 5. direction adjustment assembly; 501. bowl-shaped ball holder; 502. spherical joint; 503. auxiliary guide tube; 6. electron wind acceleration unit; 601. second positive electrode; 7. air outlet pipe; 8. serpentine pipe. DETAILED DESCRIPTION

[0052] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0053] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0054] Next, the present invention is described in detail with reference to schematic diagrams. For ease of illustration, when describing embodiments of the present invention, cross-sectional views illustrating device structures may be partially enlarged and not to scale. Furthermore, these schematic diagrams are merely illustrative and should not limit the scope of protection of the present invention. Furthermore, in actual production, three-dimensional dimensions, including length, width, and depth, should be included.

[0055] Furthermore, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in less than one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it necessarily refer to a single embodiment or a selective embodiment that is mutually exclusive of other embodiments.

[0056] Example 1, reference Figures 1-5 A large-scale segmented pre-vacuum nitriding furnace comprises a shell 1 and a nitriding furnace tank 2. The shell 1 comprises a bottom shell 101 and an upper cover 102. The bottom shell 101 and the upper cover 102 are connected to form a furnace cavity. The nitriding furnace tank 2 is arranged in the furnace cavity. The nitriding furnace tank 2 comprises at least two nitriding tank units. The plurality of nitriding tank units are detachable and spliced ​​along the front and rear directions of the nitriding furnace tank 2. A base is provided in the processing workpiece loading area of ​​the nitriding furnace tank 2. The nitriding furnace tank 2 also comprises an electron wind system. The electron wind system comprises a high-voltage power supply and at least two electron wind generating units 3.

[0057] The electron wind generating unit 3 is arranged in the nitriding furnace tank 2;

[0058] The high voltage power supply is located outside the nitriding furnace tank 2;

[0059] The electron wind generating unit 3 includes a first positive electrode 301 and a first negative electrode 302;

[0060] The air outlet of the electron wind generating unit 3 is directed toward the workpiece loading area;

[0061] It also includes a main guide cylinder 303, and the first positive electrode 301 and the first negative electrode 302 are arranged in the main guide cylinder 303 along the front-to-back direction;

[0062] The end of the main guide cylinder 303 is provided with a direction adjustment component 5;

[0063] The steering assembly 5 includes a bowl-shaped ball holder 501 provided at the end of the main steering cylinder 303;

[0064] A ball joint 502 is rotatably connected to the bowl-shaped ball holder 501;

[0065] The extended end of the spherical joint 502 is connected to the auxiliary guide cylinder 503;

[0066] The inner cavities of the main guide tube 303, the bowl-shaped ball holder 501, the ball joint 502, and the auxiliary guide tube 503 are connected to form an electronic wind flow channel with adjustable direction;

[0067] Also includes an electron wind acceleration unit 6;

[0068] The electron wind acceleration unit 6 includes a second positive electrode 601 and a second negative electrode;

[0069] The second positive electrode 601 is fixed to the inner wall of the auxiliary guide cylinder 503;

[0070] The second negative electrode is connected to the base of the workpiece loading area;

[0071] The first positive electrode 301 and the second positive electrode 601 are connected to the positive electrode of the high-voltage power supply outside the nitriding furnace tank 2 through a high-temperature resistant metal busbar;

[0072] The first negative electrode 302 and the second negative electrode are connected to the negative electrode of the high-voltage power supply outside the nitriding furnace tank 2 through a high-temperature resistant metal busbar.

[0073] In traditional processes, it is difficult for air flow to penetrate deep holes, grooves and other parts of complex workpieces, resulting in uneven nitriding of complex workpieces. Existing technologies usually compensate for insufficient nitriding of deep holes by increasing the concentration of process gas, but this will lead to over-nitriding of thin walls and protruding parts, causing deformation, and the excess process gas is directly discharged without participating in the reaction.

[0074] In this embodiment, a main guide tube 303 is provided outside the electron wind generating unit to play a wind guiding role. A bowl-shaped ball holder 501, a spherical joint 502, and a secondary guide tube 503 are provided at the end of the main guide tube 303. The main guide tube 303, the bowl-shaped ball holder 501, the spherical joint 502, and the secondary guide tube 503 cooperate to form an electron wind airflow channel with adjustable direction.

[0075] According to the geometric shape of the complex workpiece, the direction of the secondary guide tube 503 is adjusted so that the secondary guide tube 503 is directed toward the deep holes, grooves and other parts of the complex workpiece where airflow is difficult to penetrate, thereby enhancing the airflow impact strength at such parts, and the secondary guide tube 503 is directed away from the protrusions and thin-walled parts of the complex workpiece, thereby reducing the airflow impact strength at such parts.

[0076] An electron wind acceleration unit 6 is provided at the end of the electron wind generating unit 3 to accelerate the directional airflow directed to the deep holes, grooves and other parts of complex workpieces where airflow is difficult to penetrate, thereby further improving the nitriding intensity of such parts.

[0077] Through the cooperation of the electron wind generating unit 3, the direction adjustment component 5, and the electron wind accelerating unit 6, the differentiated distribution of spatial gas in a closed environment is achieved, the utilization rate of the process gas is improved without increasing the concentration of the process gas, the nitriding efficiency of the surface of the complex workpiece is improved, and the uniform nitriding of the surface of the complex workpiece is achieved.

[0078] The present invention solves the dilemma that in the traditional technology, increasing the concentration of process gas leads to over-nitriding of the bulges and thin-walled parts of the complex workpiece, while reducing the concentration of process gas leads to substandard deep-hole nitriding of the complex workpiece.

[0079] The high temperature resistant metal busbar is a busbar made of a high temperature resistant metal material, and the high temperature resistant metal material includes at least one of a nickel-based alloy or a molybdenum-titanium composite material.

[0080] The following process is used in the large-scale segmented pre-vacuum nitriding furnace:

[0081] Step 1: Place the workpiece to be processed on the base in the workpiece loading area of ​​the nitriding furnace tank 2, and electrically connect the base to the second negative electrode;

[0082] Step 2: Adjust the rotation angle of the secondary guide cylinder 503 according to the size and distribution of the workpiece, so that the secondary guide cylinder 503 faces the deep holes and grooves of the complex workpiece and avoids the protrusions and thin-walled parts of the complex workpiece;

[0083] Step 3: introducing process gas into the nitriding furnace tank 2;

[0084] Step 4: Turn on the high-voltage power supply and apply a DC voltage to the electron wind generating unit 3 and the electron wind accelerating unit 6, and cooperate with the process gas to form a directional airflow toward the deep holes and grooves of the complex workpiece, so that a uniform nitride layer is formed on the surface of the complex workpiece.

[0085] The auxiliary guide cylinder 503 is a segmented telescopic structure; the distance between the end of the auxiliary guide cylinder 503 and the surface of the workpiece on the base is between 100-200 mm.

[0086] The length of the auxiliary guide tube 503 is adjustable. For deep holes and grooves with a depth greater than 150mm on the surface of complex workpieces, the distance between the end of the auxiliary guide tube 503 and the workpiece surface is shortened to 100mm to strengthen the airflow intensity of the electron wind flow to this part. For deep holes and grooves with a depth less than 50mm on the surface of complex workpieces, the distance between the end of the auxiliary guide tube 503 and the workpiece surface is expanded to 200mm to reduce the airflow intensity of the electron wind flow to this part. Without increasing the gas concentration, the uniformity of nitriding is improved, solving the contradiction between insufficient long-distance penetration and close-range overheating and deformation in the traditional nitriding process.

[0087] The main guide tube 303 is fixed in the nitriding furnace tank 2 through the high temperature resistant insulating bracket 304, and the rotation of the auxiliary guide tube 503 does not interfere with the heating plate in the nitriding furnace body.

[0088] The process gas is a nitrogen-containing reaction gas, preferably at least one selected from ammonia and nitrogen-hydrogen mixed gas.

[0089] The plurality of electron wind generating units 3 are distributed along the front-to-back direction and the circumferential direction of the nitriding furnace receptacle 2 to ensure airflow coverage in the longitudinal direction and the circumferential direction of the receptacle.

[0090] Both the first positive electrode 301 and the second positive electrode 601 utilize multiple needle-shaped electrodes arranged circumferentially around a central axis. The first negative electrode 302 utilizes a mesh electrode. The tip effect of the needle-shaped electrodes generates an extremely strong local electric field, which more easily triggers corona discharge and improves ionization efficiency. The mesh electrode provides a continuous equipotential surface, eliminating localized distortion of the needle-shaped tip electric field and enhancing the uniformity of the electron wind distribution.

[0091] Both the needle electrode and the mesh electrode are made of high-temperature resistant metal materials; the high-temperature resistant metal materials used for the needle electrode include at least one of molybdenum, tungsten or their alloys; the high-temperature resistant metal materials used for the mesh electrode include at least one of molybdenum or molybdenum alloys.

[0092] The bowl-shaped ball holder 501 has a bolt hole at the position covering the spherical joint 502, and a locking bolt is installed in the bolt hole. The end of the locking bolt is provided with a pressure block that contacts the spherical joint 502, pushes the secondary guide cylinder 503, and after adjusting its rotation angle, rotate the locking bolt so that its end cooperates with the pressure block to fix the deflection angle of the spherical joint 502 through radial compression force.

[0093] The second negative electrode has a threaded hole running through it, and the base has a through-hole with a fixing bolt inserted into it. The base is connected to the second negative electrode via the fixing bolt that enters the threaded hole. Place the second negative electrode on the base, and insert the fixing bolt through the through-hole and into the threaded hole to press the second negative electrode against the base.

[0094] The needle-shaped electrode is designed with multiple grooves, ranging in depth from 10-20μm and spacing from 50-100μm. The edges of the grooves create localized electric field enhancement zones, improving the ionization efficiency of process gases flowing through the field. The groove structure also disperses the discharge points across multiple microscopic regions, avoiding arcing caused by current concentration. This improves discharge stability and ion generation efficiency, while also optimizing electron flow uniformity.

[0095] Multiple air outlet pipes 7 are installed within the nitriding furnace receptacle 2. The air inlet ends of the air outlet pipes 7 are connected to process gas delivery pipelines located outside the nitriding furnace body. The air outlet pipes 7 are directed toward the workpiece loading area within the nitriding furnace receptacle 2. The air outlet pipes 7 are spaced apart from the electron wind generating unit 3. This reduces the likelihood that newly injected process gas at room temperature will directly impact the workpiece surface under the action of the electron wind generating unit 3 and the electron wind accelerating unit 6, thereby reducing the possibility that unevenly heated and cooled process gas will impact the workpiece surface and form microcracks.

[0096] The outlet end of the air outlet pipe 7 is detachably connected to a serpentine pipe 8 via a high-temperature resistant flange; the serpentine pipe 8 is fixed to the inner wall of the nitriding furnace tank 2; the outlet of the serpentine pipe 8 is not less than 200 mm and not more than 500 mm from the first positive electrode 301, and the outlet direction of the serpentine pipe 8 is toward the workpiece loading area. The process gas entering the air outlet pipe 7 passes through the serpentine pipe 8 and is discharged from the outlet end of the serpentine pipe 8 toward the workpiece. The provision of the serpentine pipe 8 promotes heat exchange, increases the initial temperature of the process gas entering the nitriding furnace tank 2, and further reduces the possibility of newly injected process gas at room temperature directly impacting the workpiece surface. The outlet of the serpentine pipe 8 is not less than 200 mm from the first positive electrode 301 to prevent premature ionization of the process gas. The outlet of the serpentine pipe 8 is not more than 500 mm from the first positive electrode 301 to prevent the newly injected process gas from being too far away from the electric field, thereby reducing the ion recombination rate.

[0097] During use, before the workpiece to be processed is subjected to nitriding treatment, the workpiece to be processed is placed on the base of the workpiece loading area of ​​the nitriding furnace tank 2, and the workpiece surface is electrically connected to the second negative electrode. According to the geometric parameters of the complex workpiece surface, the secondary guide cylinder 503 is pushed and its rotation angle is adjusted so that the secondary guide cylinder 503 faces the deep holes and grooves of the complex workpiece and avoids the protrusions and thin-walled parts of the complex workpiece. Then, the locking bolt is rotated so that its end cooperates with the pressure block to fix the deflection angle of the spherical joint 502 through radial compression force.

[0098] The nitriding furnace tank 2 is sealed, and process gas is introduced into the nitriding furnace tank 2. The process gas passes through the air outlet pipe 7 and the serpentine pipe 8 in sequence along the flow direction, and flows into the nitriding furnace tank 2 from the air outlet of the serpentine pipe 8, and freely diffuses in the nitriding furnace tank 2. The serpentine pipe 8 is provided to promote heat exchange and increase the initial temperature when entering the nitriding furnace tank 2;

[0099] Turn on the high-voltage power supply and apply a DC voltage to the electron wind generating unit 3 and the electron wind accelerating unit 6. The electron wind generating unit 3 cooperates with the electron wind accelerating unit 6 to ionize the process gas flowing through the electric field after diffusion, and cooperates with the nearby process gas to form a high-temperature, directional airflow toward the deep holes and grooves of the complex workpiece, thereby improving the nitriding intensity of the part. The protruding parts and thin-walled parts of the complex workpiece are directly exposed to the diffused process gas, reducing the impact intensity of the airflow at the part, and achieving uniform nitriding on the surface of the complex workpiece.

[0100] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A segmented large-scale pre-vacuum nitriding furnace, comprising a shell (1) and a nitriding furnace tank (2), wherein the shell (1) comprises a bottom shell (101) and an upper cover (102), wherein the bottom shell (101) and the upper cover (102) are connected to form a furnace cavity, wherein the nitriding furnace tank (2) is arranged in the furnace cavity, wherein the nitriding furnace tank (2) comprises at least two nitriding tank body units, wherein the plurality of nitriding tank body units are detachably connected along the front-rear direction of the nitriding furnace tank (2), and a base is provided in a workpiece loading area of ​​the nitriding furnace tank (2), wherein the nitriding furnace tank (2) is characterized in that: Also included is an electron wind system, which includes a high-voltage power supply and at least two electron wind generating units (3); The electron wind generating unit (3) is arranged in the nitriding furnace tank (2); The high-voltage power supply is arranged outside the nitriding furnace tank (2); The electron wind generating unit (3) comprises a first positive electrode (301) and a first negative electrode (302); The air outlet of the electron wind generating unit (3) faces the processing workpiece loading area; It also includes a main guide cylinder (303), wherein the first positive electrode (301) and the first negative electrode (302) are arranged in the main guide cylinder (303) along the front-to-back direction; A direction adjustment component (5) is provided at the end of the main guide cylinder (303); The steering assembly (5) comprises a bowl-shaped ball holder (501) provided at the end of the main steering cylinder (303); A spherical joint (502) is rotatably connected to the bowl-shaped ball holder (501); The extended end of the spherical joint (502) is connected to a secondary guide cylinder (503); The inner cavities of the main guide tube (303), the bowl-shaped ball holder (501), the spherical joint (502), and the auxiliary guide tube (503) are connected to form an electronic wind flow channel with adjustable direction; Also included is an electron wind acceleration unit (6); The electron wind acceleration unit (6) comprises a second positive electrode (601) and a second negative electrode; The second positive electrode (601) is fixed to the inner wall of the auxiliary guide cylinder (503); The second negative electrode is connected to a base in the workpiece loading area; The first positive electrode (301) and the second positive electrode (601) are connected to the positive electrode of a high-voltage power supply outside the nitriding furnace tank (2) via a high-temperature resistant metal busbar; The first negative electrode (302) and the second negative electrode are connected to the negative electrode of the high-voltage power supply outside the nitriding furnace tank (2) via a high-temperature resistant metal busbar.

2. The large-scale segmented pre-vacuum nitriding furnace according to claim 1 is characterized in that: The following process is used: Step 1: placing the workpiece to be processed on a base in the processing workpiece loading area of ​​the nitriding furnace tank (2), wherein the base is electrically connected to the second negative electrode; Step 2: adjusting the rotation angle of the auxiliary guide cylinder (503) according to the size and distribution of the workpiece so that the auxiliary guide cylinder (503) faces the deep hole and groove of the complex workpiece and avoids the protrusion and thin-walled part of the complex workpiece; Step 3: introducing process gas into the nitriding furnace tank (2); Step 4: Turn on the high-voltage power supply and apply a DC voltage to the electron wind generating unit (3) and the electron wind accelerating unit (6), and form a directional airflow toward the deep holes and grooves of the complex workpiece with the process gas, so that a uniform nitride layer is formed on the surface of the complex workpiece.

3. The large-scale segmented pre-vacuum nitriding furnace according to claim 2, characterized in that: The auxiliary guide cylinder (503) is a segmented telescopic structure; The distance between the end of the secondary guide cylinder (503) and the surface of the workpiece on the base is between 100-200 mm.

4. The large-scale segmented pre-vacuum nitriding furnace according to claim 3 is characterized in that: The plurality of electron wind generating units (3) are distributed along the front-to-back direction and the circumferential direction of the nitriding furnace tank (2).

5. The large-scale segmented pre-vacuum nitriding furnace according to claim 4, characterized in that: The first positive electrode (301) and the second positive electrode (601) both use a plurality of needle-shaped electrodes; A plurality of needle-shaped electrodes are arranged circumferentially around a central axis; The first negative electrode (302) is a mesh electrode.

6. The large-scale segmented pre-vacuum nitriding furnace according to claim 5, characterized in that: The needle-shaped electrode and mesh-shaped electrode are both made of high-temperature resistant metal materials; The high temperature resistant metal material used for the needle electrode includes at least one of molybdenum, tungsten or their alloys; The high-temperature resistant metal material used for the mesh electrode includes at least one of molybdenum and a molybdenum alloy.

7. The large-scale segmented pre-vacuum nitriding furnace according to claim 6, characterized in that: A plurality of grooves are provided on the surface of the needle-shaped electrode; The grooves have a depth of 10-20 μm and a spacing of 50-100 μm.

8. The large-scale segmented pre-vacuum nitriding furnace according to claim 1 is characterized in that: A plurality of air outlet pipes (7) are provided in the nitriding furnace tank (2); The air inlet end of the air outlet pipe (7) is connected to a process gas delivery pipeline located outside the nitriding furnace body; The air outlet direction of the air outlet pipe (7) is toward the processing workpiece loading area of ​​the nitriding furnace tank (2); The air outlet pipe (7) and the electron wind generating unit (3) are arranged at intervals.

9. The large-scale segmented pre-vacuum nitriding furnace according to claim 8, characterized in that: The outlet end of the air outlet pipe (7) is detachably connected to a serpentine pipe (8) via a high-temperature resistant flange; The serpentine tube (8) is fixed to the inner wall of the nitriding furnace tank (2); The air outlet of the serpentine tube (8) is not less than 200 mm and not more than 500 mm away from the first positive electrode (301), and the air outlet direction of the serpentine tube (8) is toward the processing workpiece loading area.

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